Stoker furnace construction



Dec. 4, 1934. R. c. DENNY STOKER FURNACE CONSTRUCTION Filed Aug. 7, 1931Patented Dec. 4, 1934 UNITED STATES PATENT. OFFICE Detrlck Company, ofIllinois IIL, a corporation Application August '1, 1931, Serial No.555,673

15 Claims. (CI. 11H.)

This invention relates to the construction of large furnaces, such asboiler furnaces, more particularly to furnaces which are fired by chaingrate stokers.

In furnaces which are equipped with chain grate stokers, the sides ofthe stokers ordinarily are associated quite closely with furnace wallportions, and in most cases it is desirable to have the furnace wallportions overlap the marginal parts of the chain grate. It is desirableto minimize as much as possible the clearance or space between the chaingrate and such overlapping wall portions in order to prevent the smallfuel from working in between them. At the same time it is necessary thatsome clearance be maintained, in order that the overlapping wallportions may not drag on the moving grate. Heretofore it has beencustomary to provide metallic ledge plates along the sides of thestokers, which ledge plates project a suitable distance across themargins of the grate and form supports for superimposed portions of thewall, said ledge plates sometimes being supported on the side frame ofthe stoker, and sometimes imbedded in and supported on the lower portionof the masonry wall alongside the stoker. The interior wall portionsimmediately beside the stoker are subjected to erosive and temperatureconditions which are likely to wear them out rather rapidly andnecessitate their replacement. The ledge plates are also subject todestructive conditions of abrasion and high temperatures and have to bereplaced from time to time.

One of the general objects of the present invention is the provision ofa furnace structure wherein ledge plates are securely maintained in thedesired relationship to the grate and the wall, and at the same time maybe quickly and easily removed and replaced without involving thedismantling of any of the associated wall or stoker portions.

Another object is the provision of a construction facilitating theinstallation, maintenance and repair of the furnace wall portions inassociation with the ledge plate and stoker and particularly adapted tocontribute to the durability of the wall portions and maintain thedesired relationship between the wall portions, the ledg plate and thestoker.

Another object is the provision of a construction which will render thestoker and the ledge plates easily accessible from the outside of thefurnace and also render the wall and the stoker quite independent ofeach other in the matter of support.

Another object is the provision of a construction which will permit theweight of the stoker side frame to be reduced.

Another object is the provision of a construction which is particularlyadapted to accommodate the wind boxes or plenum boxes of forced draftstokers and minimize the floor area requisite for their installation inconjunction with the furnace.

Other and further objects will be pointed out 85 or indicatedhereinafter or will be apparent to one skilled in the art upon anunderstanding of the invention or its employment in use.

For aid in explanation of the invention I show in the accompanyingdrawing forming a part of this specification certain forms ofconstruction embodying the invention, but it is to be understood thatthese are presented entirely for the purpose of illustration and neitherthey nor the following descriptions of them are to be construed in anyfashion calculated to limit the appended claims short of the true andmost comprehensive scope of the invention in the art.

In said drawing, I

Fig. 1 represents a part sectional elevation of a0 a boiler furnacehaving a chain grate stoker, the section being taken transversely of aportion of the furnace chamber and stoker;

Fig. 2 is a detail, on a scale somewhat larger than that of Fig. 1,showing features of the assog5 ciated stoker, wall and ledge platestructure; and

Fig. 3 is a detail in the nature of a horizontal section taken onapproximately line 3-3 of Fig. 2.

The nature of the invention will be most readily understood from adescription of the illustrative embodiments here shown. The referencenumeral 10 designates generally a portion of the furnace chamber, at thelower portion of which is disposed the chain grate stoker, which may beof any of various forms. 11 designates the upper flight, and thereference numeral 11' the lower flight, of the chain grate, which isactuated in any suitable fashion to convey the fuel which is supportedas a bed on the upper flight. The reference numeral 12 designates one ofthe side frames of the stoker, which is supported on a suitablefoundation 14 and provided with a ledge 15 which supports a wear strip16 upon which travels the marginal portion of the chain grate in theupper flight.

On each of the opposite sides of the furnace is disposed a row ofupright or column members 1'7, which are spaced apart from one anotherand connected by transverse frame members 18 which are spaced apart oneabove another. Hangers 19 110 The reference numeral 95 are supported inrows on the transverse frame members, each hanger having its upper endhooked onto one of said members and having its lower end bearing againstthe inner side of the transverse member therebelow. Each hanger has ashelf 19 near its bottom portion 'and a bar-like body portion extendingupwardly therefrom and provided along its inner margin with laterallyextending flanges. Refractories 20 having T- shaped slots at their outerends are supported on the hangers and anchored thereon by engagement ofsaid hanger flanges in the T-shaped slots. These features of the wallconstruction are in general such as illustrated and described in U. S.patent to Foltz No. 1,747,822. Refractories supported on the severalrows of hangers form wall sections associated one above another andsupported independently of one another, to constitute a continuousfurnace wall spaced inwardly away from the frame members 17 and 18 whichconstitute the wall supporting structure.

To form the wall zone immediately adjacent and above the stoker, a rowof hangers 21 is arranged, each hanger having a hook portion 21 at itsupper end which is hooked onto one of the transverse members 18, and anoutwardly extending arm 21 at its lower end which abuts the inner edgeof a transverse member 18', and engages, by a hook, over the innerupstanding flange of said transverse member. The upright portion of eachhanger 21 includes a web 21 provided at its inner edge with laterallyextending flanges 21 which are offset from one another seriatim. 'I'hehanger has at its lower end an inwardly extending shelf portion 21 whichis maintained in a horizontal position when the hanger is supported onthe transverse members as above described. The hangers 21 are disposedat intervals, as illustrated in Fig. 3, and each supports a. stack ofrefractories 22 which are formed at their Outer ends with T-shaped slotswhich receive the flange portions 21 and web portions 21, whereby therefractories are anchored against displacement inwardly from the hanger.The lowermost refractory rests on the shelf 21 and has a portiondepending downwardly across the inner margin of that shelf. Thedimensions of the hangers 21 and of the refractories supported thereonare such that the lowermost refractories extend for a distance over themargin of the chain grate 11, and the refractories on juxtaposed hangersare disposed with their lateral sides in abutment so as to form a wallsection along and immediately adjacent the stoker grate, the inner faceof said section being corbelled outwardly to its junction with thesuperjacent wall section. The'uppermost course of this corbelled orbottom wall section is made up of refractories 24 which may be of theform and provided with the retaining arrangements illustrated anddescribed in U. S. patent to Sheahan No. 1,767,406. The adjoiningportions of the several sections may be constructed in the fashiondescribed in the last mentioned patent, to afford expansion joints whichwill accommodate the expansion of the several sections independently.

A plurality of ledgeplate sections 25 are provided, same being formed ofcast iron or other suitable heat-resisting metal. The respective ledgeplate sections preferably are of a length such as to span a plurality ofthe hangers 21. They preferably are transversely slotted, as at 25*, fora distance inwardly from their inner margins, to afford expansionspaces. These ledge plate sections are disposed end to end in ahorizontal series, and are supported on the hangers 21 by means of bolts26 in the lateral flanges of the hanger arms 21*. Their dimensions andarrangement are such that they extend across the stoker side frame 12and project a desired distance over the margin of the chain grate 11;where they underlie the lowermost refractories 22 of the bottom wallsection. By the employment of shims or washers between the ledge platesections and the hanger arms 21 as at 27, the ledge plates may beaccurately positioned so as to provide exactly the small clearancedesired between them and the chain grate. The space between the uppersurfaces of the ledge plate sections and the lowermost refractories 22may be filled with a suitable refractory packing. If desired, the ledgeplate sections may be provided with depending flanges 25 which may beabutted against an outwardly presented flange or surface of the stokerside frame in order to form a close joint to prevent gas or air leakageeither outwardly or inwardly along the line of the grate.

In various types of forced draft chain grate stokers, wind boxes areprovided alongside the stoker or the furnace wall for conveying airunder pressure to the space under the upper flight of the grate, saidair being introduced below the grate through openings 12 in the stokerside frames. With the present construction such wind boxes may beprovided as indicated at 28 immediately alongside the stoker framesandbetween them and the upright frame members 17, and may be made of anylight metal, as they carry no Weight.

The construction affords many distinct advantages. The ledge platesections may be removed and replaced with facility, entirely from theoutside of the furnace, and without involving the dismantling of anyportion of the wall or stoker. Likewise, the wall portions adjacent thestoker may be removed and replaced without requiring the dismantling ofsuperjacent wall parts and without involving any displacement of theledge plates. As pointed out above, accurate positioning of the ledgeplates with respect to the chain grate is very easily accomplished, andtheir vertical position may be changed whenever desired or necessary.The stoker side frame is entirely relieved of the weight of the wall orthe ledge plate, and consequently may be made appreciably lighter thanis necessary in constructions where it is required to carry some of thewall load. Areas adjacent the stoker which are generally occupied by aportion of the wall are rendered available for installation of auxiliaryelements of the stoker. The ledge plate is maintained in definiteposition with respect to the grate, so that their relationship cannot bedisturbed by expansion or contraction of the wall refractories or bytheir distortion or softening from heat. The ledge plates have quiteextensive areas exposed to circulation of air outside the furnace,whereby they may be effectively cooled and their rapid destruction byheat avoided.

What I claim is:

1. In a furnace having a chain grate stoker, the combination of a framespaced laterally from the stoker, a ledge plate supported on the frameand extending over a marginal portion of the stoker, a refractory wallportion supported on the frame independently of the ledge plate andoverlying the same to form a protection therefor, and means retainingthe ledge plate-and refractory wall portion in association yetpermitting their removal independently of each other.

2. In a furnace structure having a chain grate stoker, the combinationof a frame spaced laterally from the stoker, a ledge plate supported onthe frame and extending over a marginal portion of the stoker grate,refractories supported on the frame above the ledge plate andindependently thereof to form a wall portion extending longitudinally ofand projecting over a marginal portion of the grate and forming aprotective covering for the ledge plate, and means anchoring therefractories and ledge plate in association yet permitting their removalindependently of each other.

3. A furnace structure as specified in claim 2 and including attachingmembers connecting the ledge plate to the frame and disposed in aposisition accessible at the outer side of the wall portion to permitdemounting and replacing of the ledge plate from the outside of thefurnace.

4. A furnace structure as specified in claim 2 and wherein the ledgeplate is associated with the stoker side frame to afford an intermediatechannel for travel of the stoker grate and said wall portion overliessaid channel.

5. A furnace structure as specified in claim 2 and wherein the ledgeplate is formed of sections and the sections are demountable severallyfrom the frame.

6. A furnace structure as specified in claim 2 and including hangersmounted onthe frame to one side of the stoker and forming intermediateconnections between the ledge plate, refractory wall portion and frame.

7. A furnace structure as specified in claim 2 and including hangersconnected to the frame at one side of the stoker, the refractories andledge plate being anchored to said hangers, and the hangers holding therefractories and ledge plate spaced away from the frame.

8. In a furnace, the combination with a chain grate stoker and arefractory wall portion overhanging a marginal portion of the stokergrate, of a ledge plate projecting over said marginal portion of thegrate and underlying said wall portion, means supporting the ledge platedemountably, and means supporting said wall portion independently of theledge plate to permit removal of the latter outwardly of the furnacefrom between said grate and wall portions.

9. In a furnace, the combination with a stoker and refractory wall inoverlapping relationship, of a ledge plate interposed betweenoverlapping portions of the two and overlapping a portion of the stokergrate, said ledge plate being secured in position independently of thewall and stoker having extensive surface portions exposed to aircirculation outside the furnace chamber.

10. In a furnace having achain grate stoker, the combination of arefractory wall portion overlapping a lateral portion of the stoker andhaving its inner side in proximity to the chain grate, a ledge plateunderlying said overlapping wall portion, and means supporting andanchoring said wall portion and ledge plate independently and permittingremoval of either without removal of the other.

11. A furnace structure as specified in claim 10 and includingrefractory packing material interposed between the ledge plate andoverlying refractory wall portion.

12. In a chain grate stoker furnace having a side wall disposedoutwardly from a margin of the grate, a series of hangers supported independently of the stoker along the-side thereof, a ledge plate removablysupported on the hangers and projecting inwardly across a marginalportion of the grate, and courses of refractories supported by saidhangers independently of the ledge plate to form a wall portion havingits upper terminus adjoining the lower terminus of said side wall andits lower portion overlying and forming a protective covering for theledge plate over the grate, the refractories having anchorage on thehangers whereby they are retained in position, and the ledge platebeing, removable outwardly from the furnace while the refractories arein place.

13. In a chain grate stoker furnace, in combination, a frame disposedalongside the stoker, a horizontally running series of hangers supportedon the frame adjacent the side of the stoker, refractories supported onthe hangers and having anchorage thereon whereby they are retained inposition to form a lateral retainer for a fuel bed on the grate, and aledge plate supported on the hangers and extending inwardly over amarginal portion of the grate in juxtaposition to the refractories, saidledge plate being demountable from the hangers and removable outwardlyfrom the furnace while said refractories and grate remain in place.

14. In a furnace having a chain grate stoker,-

the combination of a frame spaced laterally from the stoker, a series ofhangers supported on the ROBERT C. DENNY.

